Early-versus-Late Endovascular Stroke Treatment: Similar Frequencies of Nonrevascularization and Postprocedural Cerebrovascular Complications in a Large Single-Center Cohort Study.

BACKGROUND AND PURPOSE: Endovascular treatment of acute ischemic stroke is now performed more frequently in the late window in radiologically selected patients. However, little is known about whether the frequency and clinical impact of incomplete recanalization and postprocedural cerebrovascular complications differ between early and late windows in the real world. MATERIALS AND METHODS: We retrospectively reviewed all patients with acute ischemic stroke receiving endovascular treatment within 24 hours from 2015 to 2019 and included in the Acute STroke Registry and Analysis of Lausanne. We compared rates of incomplete recanalization and postprocedural cerebrovascular complications (parenchymal hematoma, ischemic mass effect, and 24-hour re-occlusion) in the early (<6 hours) versus late window (6-24 hours, including patients with unknown onset) populations and correlated them with the 3-month clinical outcome. RESULTS: Among 701 patients with acute ischemic stroke receiving endovascular treatment, 29.2% had late endovascular treatment. Overall, incomplete recanalization occurred in 56 patients (8%), and 126 patients (18%) had at least 1 postprocedural cerebrovascular complication. The frequency of incomplete recanalization was similar in early and late endovascular treatment (7.5% versus 9.3%, adjusted P =.66), as was the occurrence of any postprocedural cerebrovascular complication (16.9% versus 20.5%, adjusted P = .36). When analyzing single postprocedural cerebrovascular complications, rates of parenchymal hematoma and ischemic mass effect were similar (adjusted P = .71, adjusted P = .79, respectively), but 24-hour re-occlusion seemed somewhat more frequent in late endovascular treatment (4% versus 8.3%, unadjusted P = .02, adjusted P = .40). The adjusted 3-month clinical outcome in patients with incomplete recanalization or postprocedural cerebrovascular complications was comparable between early and late groups (adjusted P = .67, adjusted P = .23, respectively). CONCLUSIONS: The frequency of incomplete recanalization and of cerebrovascular complications occurring after endovascular treatment is similar in early and well-selected late patients receiving endovascular treatment. Our results demonstrate the technical success and safety of endovascular treatment in well-selected late patients with acute ischemic stroke.

Predictors of Endovascular Treatment Procedural Complications in Acute Ischemic Stroke: A Single-Center Cohort Study.

BACKGROUND AND PURPOSE: Procedural complications occur in 4%-29% of endovascular treatments in acute ischemic stroke. However, little is known about their predictors and clinical impact in the real world. We aimed to investigate the frequency and clinical impact of procedural complications of endovascular treatment and identify associated risk factors. MATERIALS AND METHODS: From 2015-2019, we retrospectively reviewed all patients with acute ischemic stroke receiving endovascular treatment within 24 hours included in the Acute STroke Registry and Analysis of Lausanne. We identified patients having an endovascular treatment procedural complication (local access complication, arterial perforation, dissection or vasospasm, and embolization in a previously nonischemic territory) and performed logistic regression analyses to identify associated predictors. We also correlated procedural complications with long-term clinical outcome. RESULTS: Of the 684 consecutive patients receiving endovascular treatment, 113 (16.5%) had at least 1 procedural complication. The most powerful predictors were groin puncture off-hours (OR = 2.24), treatment of 2 arterial sites (OR = 2.71), and active smoking (OR = 1.93). Patients with a complication had a significantly less favorable short-term clinical outcome (Δ-NIHSS score of -2.2 versus -4.33, P-value adjusted < .001), but a similar long-term clinical outcome (mRS at 3 months = 3 versus 2, P-value adjusted = .272). CONCLUSIONS: Procedural complications are quite common in endovascular treatment and lead to a less favorable short-term but similar long-term outcome. Their association with treatment off-hours and at 2 arterial sites requires particular attention in these situations to optimize the overall benefit of endovascular treatment.

Should posterior cerebral artery occlusions be recanalized? Insights from the Trevo Registry.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the safety and effectiveness of mechanical thrombectomy (MT) in patients with acute ischaemic stroke related to isolated and primary posterior cerebral artery (PCA) occlusions amongst the patients enrolled in the multicentre post-market Trevo Registry. METHOD: Amongst the 2008 patients enrolled in the Trevo Registry with acute ischaemic stroke due to large vessel occlusion treated by MT, 22 patients (1.1%) [10 females (45.5%), mean age 66.2 ± 14.3 years (range 28-91)] had a PCA occlusion [17 P1 (77.3%) and five P2 occlusions (22.7%)]. Recanalization after the first Trevo (Stryker, Fremont, CA, USA) pass and at the end of the procedure was rated using the modified Thrombolysis in Cerebral Infarction (mTICI) score. Procedure-related complications (i.e. groin puncture complication, perforation, symptomatic haemorrhage, embolus in a new territory) were also recorded. The modified Rankin Scale at 90 days was assessed. RESULTS: Median National Institutes of Health Stroke Scale at admission was 14 (interquartile range 8-16). Stroke aetiology was cardio-embolic in 68.2% of cases. Half of the patients (11/22) received intravenous tissue plasminogen activator. 54.5% of the patients were treated under general anaesthesia. Reperfusion (i.e. mTICI 2b or 3) after first pass was obtained in 65% of cases. Final mTICI 2b-3 reperfusion was obtained in all cases. Only one (4.5%) procedure-related complication was recorded (puncture site) that resolved after surgery. At 90-day follow-up, modified Rankin Scale 0-2 was obtained in 59% of the patients and 9.1% died within the first 3 months after MT. CONCLUSION: Mechanical thrombectomy for PCA occlusions seems to be safe (<5% procedure-related complications) and effective. Larger repository datasets are needed.

A novel next generation sequencing assay as an alternative to currently available methods for hepatitis C virus genotyping.

Chronic HCV infection is one of the leading causes of liver-related death and in many countries it is a primary reason for having a liver transplant. HCV genotype identification has long been used in the clinical practice, since different genotypes have different response rates and required different doses and durations of IFN/RBV treatment; moreover both the frequency and the pattern of resistance to different Direct-Acting Antivirals (DAAs) classes are subtype specific. Hence the necessity to make an accurate HCV subtyping becomes a fundamental tool to optimize current and future clinical management of HCV infected subjects. In the present study the performance of a next generation sequencing (NGS: based on the Ion Torrent Platform-Vela Sentosa SQ 301 sequencer) HCV genotyping assay has been evaluated. The current method targets a region of the NS5B gene and it is the unique NGS based market CE-IVD assay. As a comparative method a commercial method based on the detection via reverse hybridization of 5'UTR and core regions (Versant HCV Genotype 2.0 Assay, LiPA, Siemens) was selected. A total 207 plasma samples from HCV infected individuals were used. No selection was made for these samples that were submitted for routine HCV genotyping. The results show Vela NGS assay assigns major number of HCV subtypes with respect LiPA. Concerning genotype 1 and 3, the discrepancy of assigned subtypes for LiPA with respect to Vela NGS assay is not relevant (1.8% and 2%, respectively); in contrast, the difference of assigned subtypes for genotypes 2 and 4 is very high (96.6% and 100%, respectively). The resistance mutations data, except for 1a and 1b subtypes, remain scarce; the future relevant challenge will be to identify subtypes-specific drug resistance mutations, which are essential to create highly personalized therapeutic pathways.

Hepatitis C virus: life cycle in cells, infection and host response, and analysis of molecular markers influencing the outcome of infection and response to therapy.

Hepatitis C virus (HCV) is a major global health burden accounting for around 170 million chronic infections worldwide. Since its discovery, which dates back to about 30 years ago, many details of the viral genome organization and the astonishing genetic diversity have been unveiled but, owing to the difficulty of culturing HCV in vitro and obtaining fully susceptible yet immunocompetent in vivo models, we are still a long way from the full comprehension of viral life cycle, host cell pathways facilitating or counteracting infection, pathogenetic mechanisms in vivo, and host defences. Here, we illustrate the viral life cycle into cells, describe the interplay between immune and genetic host factors shaping the course of infection, and provide details of the molecular approaches currently used to genotype, monitor replication in vivo, and study the emergence of drug-resistant viral variants.

A Direct Aspiration, First Pass Technique (ADAPT) versus Stent Retrievers for Acute Stroke Therapy: An Observational Comparative Study.

BACKGROUND AND PURPOSE: Mechanical thrombectomy with stent retrievers is now the standard therapy for selected patients with ischemic stroke. The technique of A Direct Aspiration, First Pass Technique for the Endovascular Treatment of Stroke (ADAPT) appears promising with a high rate of recanalization. We compared ADAPT versus stent retrievers (the Solitaire device) for efficacy and safety as a front-line endovascular procedure. MATERIALS AND METHODS: We analyzed 243 consecutive patients with large intracranial artery occlusions of the anterior circulation, treated within 6 hours with mechanical thrombectomy by either ADAPT or the Solitaire stent. Th primary outcome was complete recanalization (modified TICI ≥ 2b); secondary outcomes included complication rates and procedural and clinical outcomes. RESULTS: From November 2012 to June 2014, 119 patients were treated with stent retriever (Solitaire FR) and 124 by using the ADAPT with Penumbra reperfusion catheters. The median baseline NIHSS score was the same for both groups (Solitaire, 17 [interquartile range, 11-21] versus ADAPT, 17 [interquartile range, 12-21]). Time from groin puncture to recanalization (Solitaire, 50 minutes [range, 25-80 minutes] versus ADAPT, 45 minutes [range, 27-70 minutes], P = .42) did not differ significantly. However, compared with the Solitaire group, patients treated with ADAPT achieved higher final recanalization rates (82.3% versus 68.9%; adjusted relative risk, 1.18; 95% CI, 1.02-1.37; P = .022), though differences in clinical outcomes between the cohorts were not significant. Use of an adjunctive device was more frequent in the ADAPT group (45.2% versus 13.5%, P < .0001). The rate of embolization in new territories or symptomatic hemorrhage did not differ significantly between the 2 groups. CONCLUSIONS: Front-line ADAPT achieved higher recanalization rates than the Solitaire device. Further randomized controlled trials are warranted to define the best strategy for mechanical thrombectomy.

Endovascular treatment of posterior fossa arteriovenous malformations.

Infratentorial arteriovenous malformations (AVM) are rare, representing only 7-15% of cerebral AVM. The concentration of eloquent neurological structures and the high rate of bleeding presentation of AVM in this location complicate the management of such lesions. New therapeutic options, especially in endovascular therapy, have fundamentally modified the treatment strategy and also the outcome of posterior fossa AVM. Between 1999 and 2013, baseline, clinical and angiographic data of cerebral AVM were prospectively collected. We analyzed data from patients treated for a posterior fossa AVM, focusing on risk factors for bleeding, and clinical and angiographic outcomes. Sixty-nine patients (mean age 34 years, male to female ratio 2:1) were consecutively treated for an infratentorial AVM. Fifty-seven presented with hemorrhage, six with focal neurologic deficits, and the remaining six patients were diagnosed incidentally. The Spetzler-Martin grade was < 3 in 39 (56.5%) patients. Associated aneurysms were noted in 43.5% of patients. All patients were treated using endovascular procedures, associated with microsurgical resection in nine patients and with stereotactic radiosurgery in six. Mean follow-up was 28.5 months, with angiographic exclusion of the AVM in 72.5% of patients; 21.7% of patients presented a modified Rankin Score ⩾ 3 at follow-up. Endovascular embolization seems to be a secure approach for posterior fossa AVM although a large number of sessions are necessary to achieve complete obliteration. Multi-disciplinary discussion and management is crucial to obtain the best cure rate without increasing procedural risks.

Flow Diversion versus Standard Endovascular Techniques for the Treatment of Unruptured Carotid-Ophthalmic Aneurysms.

BACKGROUND AND PURPOSE: Over the past few years, flow diversion has been increasingly adopted for the treatment of intracranial aneurysms, especially in the paraclinoid and paraophthalmic carotid segment. We compared clinical and angiographic outcomes and complication rates in 2 groups of patients with unruptured carotid-ophthalmic aneurysms treated for 7 years by either standard coil-based techniques or flow diversion. MATERIALS AND METHODS: From February 2006 to December 2013, 162 unruptured carotid-ophthalmic aneurysms were treated endovascularly in 138 patients. Sixty-seven aneurysms were treated by coil-based techniques in 61 patients. Flow diverters were deployed in 95 unruptured aneurysms (77 patients), with additional coiling in 27 patients. Complication rates, clinical outcome, and immediate and long-term angiographic results were retrospectively analyzed. RESULTS: No procedure-related deaths occurred. Four procedure-related thromboembolic events (6.6%) leading to permanent morbidity in 1 case (1.6%) occurred in the coiling group. Neurologic complications were observed in 6 patients (7.8%) in the flow-diversion group, resulting in 3.9% permanent morbidity. No statistically significant difference was found between complication (P = .9) and morbidity rates (P = .6). In the coiling group (median follow-up, 31.5 ± 24.5 months), recanalization occurred at 1 year in 23/50 (54%) aneurysms and 27/55 aneurysms (50.9%) at the latest follow-up, leading to retreatment in 6 patients (9%). In the flow-diversion group (mean follow-up, 13.5 ± 10.8 months), 85.3% (35/41) of all aneurysms were occluded after 12 months, and 74.6% (50/67) on latest follow-up. The retreatment rate was 2.1%. Occlusion rates between the 2 groups differed significantly at 12 months (P < .001) and at the latest follow-up (P < .005). CONCLUSIONS: Our retrospective analysis shows better long-term occlusion of carotid-ophthalmic aneurysms after use of flow diverters compared with standard coil-based techniques, without significant differences in permanent morbidity.

"Y" and "X" stent-assisted coiling of complex and wide-neck intracranial bifurcation aneurysms.

BACKGROUND AND PURPOSE: Stent-assisted coiling with two stents has been described in some series for the treatment of complex and wide-neck bifurcation aneurysms. Our aim was to report our experience of a stent-assisted coiling technique with double stents in "Y" and "X" configurations, with emphasis on safety, feasibility, and efficacy. MATERIALS AND METHODS: Clinical and angiographic outcomes of patients for whom the strategic therapeutic option was the stent-assisted coiling technique in a Y or X configuration for neck scaffolding from June 2006 to June 2013 were retrospectively analyzed. RESULTS: One hundred five aneurysms in 97 patients were treated during 100 consecutive procedures. There were 54.2% (57/105) MCA, 28.6% (30/105) anterior communicating artery, 16.2% (17/105) basilar tip, and 1.0% (1/105) ICA termination aneurysms. A Y stent placement was used to treat 87 aneurysms in 85 procedures; an X stent placement was used to treat 7 aneurysms in 6 procedures, while 9 procedures failed for 11 aneurysms. There were 10.0% (10/100) procedure-related permanent neurologic deficits and 1.0% (1/100) death. The immediate angiographic controls showed a complete occlusion in 47.6% (50/105) of the aneurysms and a partial (neck or sac remnant) occlusion in 52.4% (55/105). To date, 81.0% (85/105) of the aneurysms have been followed up (mean, 17 months) with angiography, disclosing a recanalization in 5.9% (5/85) and an improvement in 42.4% (36/85). At discharge and follow-up, the mRS score was 0 in 83.5% (81/97) of patients, 1 in 4.1% (4/97), 2 in 3.1% (3/97), 3 in 4.1% (4/97), 4 in 3.1% (3/97), and 6 in 2.1% (2/97). CONCLUSIONS: Y and X stent-assisted coiling of complex and wide-neck intracranial bifurcation aneurysms is an effective technique.

Hemorrhagic complications after endovascular treatment of cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: Intracranial hemorrhage is the most severe complication of brain arteriovenous malformation treatment. We report our rate of hemorrhagic complications after endovascular treatment and analyze the clinical significance and potential mechanisms, with emphasis on cases of delayed hemorrhage after uneventful embolization. MATERIALS AND METHODS: During a 10-year period, 846 embolization procedures were performed in 408 patients with brain AVMs. Any cases of hemorrhagic complications were identified and divided into those related or unrelated to a periprocedural arterial tear (during catheter navigation or catheter retrieval). We analyzed the following variables: sex, age, hemorrhagic presentation, Spetzler-Martin grade, size of the AVM, number of embolized pedicles, microcatheter used, type and volume of liquid embolic agent injected, and the presence of a premature venous occlusion. Univariate and multivariate multiple regression analyses were performed to identify risk factors for hemorrhagic complications. RESULTS: A hemorrhagic complication occurred in 92 (11%) procedures. Forty-four (48%) complications were related to a periprocedural arterial perforation, and 48 (52%) were not. Hemorrhagic complications unrelated to an arterial perforation were located more commonly in the cerebral parenchyma, caused more neurologic deficits, and were associated with worse prognosis than those in the arterial perforation group. Only premature venous occlusion was identified as an independent predictor of hemorrhagic complication in the nonperforation group. Premature venous occlusion was significantly related to the ratio of Onyx volume to nidus diameter. CONCLUSIONS: Higher injected volume of embolic agent and deposition on the venous outflow before complete occlusion of the AVM may account for severe hemorrhagic complications.

Analysis of complications and recurrences of aneurysm coiling with special emphasis on the stent-assisted technique.

BACKGROUND AND PURPOSE: Stent-assisted coiling has expanded the treatment of intracranial aneurysms. With the use of continuously compiled data, we reviewed the role and drawbacks of stent-assisted coiling. MATERIALS AND METHODS: We compiled data from consecutive patients from 2003-2012 who underwent coiling, with or without stent assistance. Clinical and angiographic results were analyzed retrospectively. RESULTS: Of 1815 saccular aneurysms in 1505 patients, 323 (17.8%) were treated with stents (299 procedures) and 1492 (82.2%) without stents (1400 procedures). Procedure-related complications occurred in 9.4% with stents versus 5.6% without stents (P = .016, relative risk 1.5; 95% CI, 1.1-2.7). Ischemic complications were more frequent in the stent group than in the no-stent group (7.0% versus 3.5%; P = .005; relative risk, 1.7; 95% CI 1.2-2.5), as were hemorrhagic complications (2.3% versus 1.9%, P = .64). Procedure-induced mortality occurred in 2.7% (8/299) with stents versus 1.1% (15/1400) without stents (P = .029; relative risk, 2.0; 95% CI, 1.1-3.5). Logistic regression analysis identified wide-neck aneurysms as the most significant independent predictor of complications. A total of 64.1% (207/323) of aneurysms treated with stents and 70.3% (1049/1492) treated without stents have been followed, disclosing angiographic recurrence in 15.5% (32/207) versus 35.5% (372/1049), respectively (P < .0001). Logistic regression analysis showed that the presence of a stent was the most important factor for the reduction of angiographic recurrence (P < .0001; relative risk, 2.3; 95% CI, 1.6-3.3). CONCLUSIONS: The stent-assisted coiling technique is associated with a significant decrease in recurrences but a significant increase in complications. The treatment of wide-neck aneurysms remains hazardous.

Quasispecies tropism and compartmentalization in gut and peripheral blood during early and chronic phases of HIV-1 infection: possible correlation with immune activation markers.

HIV quasispecies was analysed in plasma and proviral genomes hosted by duodenal mucosa and peripheral blood cells (PBMC) from patients with early or chronic infection, with respect to viral heterogeneity, tropism compartmentalization and extent of immune activation. Seventeen HIV-1-infected combined antiretroviral therapy naive patients were enrolled (11 early infection and six chronic infection). V3 and nef genomic regions were analysed by ultra-deep pyrosequencing. Sequences were used to infer co-receptor usage and to construct phylogenetic trees. As markers of immune activation, plasma sCD14 and soluble tumour necrosis factor receptor II (sTNFRII) levels were measured. Median diversity of HIV RNA was lower in patients with early infection versus chronic infection patients. Overall, direct correlation was observed between V3 diversity and X4 frequency; V3 diversity of HIV RNA was inversely correlated with CD4 T-cell count; median sCD14 and sTNFRII values were similar in early and chronic patients, but X4 frequency of HIV RNA was directly correlated with plasma sCD14. The proportion of patients harbouring X4 variants and median intra-patient X4 frequency of proviral genomes tended to be higher in chronic infection than early infection patients. More pronounced compartmentalization of proviral quasispecies in gut compared with PBMC samples was observed in patients with early infection compared with chronic patients. The loss of gut/PBMC compartmentalization in more advanced stages of HIV infection was confirmed by longitudinal observation. More studies are needed to understand the pathogenetic significance of early HIV quasispecies compartmentalization and progressive intermixing of viral variants in subsequent phases of the infection, as well as the role of immune activation in tropism switch.

Role of neuronal and inducible nitric oxide synthases in the guinea pig ileum myenteric plexus during in vitro ischemia and reperfusion.

BACKGROUND: Intestinal ischemia and reperfusion (I/R) injury leads to abnormalities in motility, namely delay of transit, caused by damage to myenteric neurons. Alterations of the nitrergic transmission may occur in these conditions. This study investigated whether an in vitro I/R injury may affect nitric oxide (NO) production from the myenteric plexus of the guinea pig ileum and which NO synthase (NOS) isoform is involved. METHODS: The distribution of the neuronal (n) and inducible (i) NOS was determined by immunohistochemistry during 60 min of glucose/oxygen deprivation (in vitro ischemia) followed by 60 min of reperfusion. The protein and mRNA levels of nNOS and iNOS were investigated by Western-immunoblotting and real time RT-PCR, respectively. NO levels were quantified as nitrite/nitrate. KEY RESULTS: After in vitro I/R the proportion of nNOS-expressing neurons and protein levels remained unchanged. nNOS mRNA levels increased 60 min after inducing ischemia and in the following 5 min of reperfusion. iNOS-immunoreactive neurons, protein and mRNA levels were up-regulated during the whole I/R period. A significant increase of nitrite/nitrate levels was observed in the first 5 min after inducing I/R and was significantly reduced by N(ω) -propyl-l-arginine and 1400 W, selective inhibitors of nNOS and iNOS, respectively. CONCLUSIONS & INFERENCES: Our data demonstrate that both iNOS and nNOS represent sources for NO overproduction in ileal myenteric plexus during I/R, although iNOS undergoes more consistent changes suggesting a more relevant role for this isoform in the alterations occurring in myenteric neurons following I/R.

Detection of haemagglutinin D222 polymorphisms in influenza A(H1N1)pdm09-infected patients by ultra-deep pyrosequencing.

This study was aimed at establishing the genetic heterogeneity of influenza virus haemagglutinin (HA) gene quasi-species and the polymorphisms at codon 222, by application of ultra-deep pyrosequencing (UDPS) to respiratory samples from patients hospitalized for influenza A(H1N1)pdm09 infection, presenting with severe or moderate-mild disease. HA diversity was significantly higher in samples collected from patients with severe manifestations than in those from patients with moderate-mild manifestations (p 0.02). D222 polymorphism was detected in 40.7% of patients by UDPS, and in only 7.1% by Sanger sequencing. D222E, D222G, D222N and D222A were observed in 37.0%, 11.1%, 7.4% and 3.7% of patients, respectively; 10.7% of samples harboured more than two variants. The relative frequency of each single variant showed a wide range of intrapatient variation. D222G/N/A were detected, as either minor or predominant variants, only in severe cases, whereas D222E was equally represented in severe and moderate-mild infections. Other amino acid variants were observed at different positions within the analysed HA fragment. Consistent with higher heterogeneity, non-D222 variants were more frequently detected in severe cases than in moderate-mild cases. In addition, seven non-D222 mutations carried by minority variants, not previously described, were observed.

Analysis of co-receptor usage of circulating viral and proviral HIV genome quasispecies by ultra-deep pyrosequencing in patients who are candidates for CCR5 antagonist treatment.

UDPS combined with genotypic algorithms for prediction of HIV-1 co-receptor usage may provide quantitative data about the tropism of each variant present in the viral quasispecies. The aim of the present study was to assess co-receptor usage by ultra-deep pyrosequencing (UDPS), in comparison with the reference phenotypic test (Trofile), in patients who are candidates for CCR5 antagonist treatment, in both circulating and proviral HIV-1. Seventeen patients who were tested by Trofile were enrolled. UDPS of the V3 loop region was carried out on both plasma RNA and proviral DNA. Genotypic prediction of co-receptor usage was established by position-specific score matrices (PSSM) and confirmed, in discordant cases, with geno2pheno. Genetic heterogeneity of the RNA and DNA quasispecies was assessed as well. A total of 196,729 V3 sequences were considered (mean coverage per site, 6346). Concordance between phenotypic test and UDPS with PSSM was 0.82. Geno2pheno results were in line with those obtained with PSSM. Proviral quasispecies were more heterogeneous than those found in circulating HIV. In most patients eligible for CCR5 antagonist treatment, X4 variants were detected in proviral DNA, ranging from 1.0% to 52.7%. UDPS combined with genotypic algorithms for co-receptor usage prediction highlighted the presence of minority variants, with a discordant tropism with respect to the predominant population, in both circulating viral and proviral HIV. In most patients treated with Maraviroc the virological response was independent of the presence of X4 in proviral DNA. The clinical impact of minority X4 variants present in patients who are candidates for anti-CCR5 antagonists remains a crucial point to be addressed.

Comparison of real-time PCR methods for measurement of HIV-1 proviral DNA.

The use of HIV-1 DNA quantitation in cellular reservoirs to predict disease progression and treatment outcome in infected patients is hampered by the lack of standardization among the available methods. In the present study, real-time PCR methods used commonly for HIV-1 proviral DNA evaluation were compared, showing strong differences in the results, probably as a consequence of genome variability in the target regions. Standardization of HIV-1 proviral DNA quantitation assays is needed for use in clinical management of patients with HIV-1.